You don’t need no stinking water. Seriously, if your just biking around town and don’t have a need for your water bottle holder, check out the BoomBottle Speaker from Scosche ($150). The BoomBottle comes in an IPX4 case and is covered in rubber and TPU to protect it from those occasional drops and splashes. The sound is driven by two 40mm drivers and a ported base unit to provide enough volume for the noisiest environments. It also comes with Bluetooth technology and a 3.5mm jack to fit all of your headphone needs.
